I'll give Web Whiteboard another shot. Something about it didn't grab me, but I was kinda doing speed-runs on the various shared-workspace services to see what I could get away with, so it's easy to think I missed something.

Many of the elements of Miro turned out to be more intuitive than I expected, including sharing documents, and making notes. Mostly drag-and-drop from the desktop, or just start typing over an element.

Miro is definitely more powerful, with more features, and would probably be preferred for a campaign or a private game. My criteria was easy to use and no login required. Web Whiteboard does that.

Now I definitely haven't given Miro a fair shot. I got to the invite users by email and passed for what I want. There may even be a way to share with a link.

You can share with a link but it takes you to a login screen, not a whiteboard. So gamers have to be willing to make an account to see the whiteboard. (to the best of my knowledge)

Also if you are going to run a campaign that outlasts the Web Whiteboard 21 days it will cost money if you need to save the whiteboard from session to session. I believe Miro is not time limited in it's free version so that might also be a big factor. (to the best of my knowledge)

Yeah, the only notable limitation for the free version of Miro is three boards per account. Some features are turned off, but they're mostly aimed at things like productivity and workflow control.

The 21-day cap is much more problematic, as I don't run games rapidly (outside of one-shots).

Also if you're running campaigns you probably already have the emails of the players. In the Gamer+ If You Play You Win one offs I want anyone who's at Tenkars to be able to pick a pregen and be in the game. We are going to rotate DMs. We're working on the first one and my son Kier will DM that. I figure schedule 3 hrs. for a one off. Would you be interested in running one of these in the future?